Film deposition apparatus and film deposition method

ABSTRACT

A particle film deposition apparatus and method are provided, with which ultra fine particles are generated by arc heating. The generated ultra fine particles can be efficiently sucked up into a transfer tube regardless of an arc voltage, and the resulting film can be stable in shape. An evaporation material  8  to be evaporated by arc heating and to generate ultra fine particles is connected to an electrode. As other electrodes, a plurality of rods  17  each having a discharge section at the tip thereof are provided. These rods  17  are so arranged as to be directed in each different direction with respect to the evaporation material  8.

This application claims the right of priority under 35 U.S.C. §119 basedon Japanese Patent Application Nos. JP 2002-122314 filed on Apr. 24,2002 and JP2003-117358 filed on Apr. 22, 2003 which are herebyincorporated by reference herein their entirety as if fully set forthherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a film deposition apparatus and a filmdeposition method using ultra fine particles formed by arc heatingmethod.

2. Description of the Related Art

Conventionally, the film deposition apparatus of the above type isexemplified by the one having gas deposition method applied thereto.

Such a gas deposition apparatus is structured by, for example, aultra-fine particle generation chamber, a film deposition chamber, and atransfer tube for connection between the ultra-fine particle generationchamber and the film deposition chamber. In the ultra-fine particlegeneration chamber, arc heating, resistance heating, high-frequencyinduction heating, laser heating, or the like evaporates materials ininert gas atmosphere. Then, colliding the resulting evaporated materialsagainst the inert gas generates ultra fine particles, each ranging indiameter from a few nm to a few μm. The ultra-fine particle generationchamber is so set as to be higher in pressure than the film depositionchamber. Due to the pressure difference, the ultra fine particlesgenerated in the ultra-fine particle generation chamber are led to thefilm generation chamber via the transfer tube. Here, an end portion ofthe transfer tube is placed in the film deposition chamber, and the endportion is nozzle-shaped. From this nozzle, the ultra fine particles areejected at high speed toward a substrate placed in the film depositionchamber. As such, colliding the ultra fine particles against thesubstrate leads to any desired pattern in a direct manner. For details,see Japanese Patents No. 2524622, No. 1595398, No. 2632409, and No.2596434.

Such a gas deposition method has been considered applicable to varyingareas such as electrical wiring (see JP-A-5-47771), bump-shapedelectrodes (see JP-A-10-140325), and joint members (see JP-A-7-37512).

The ultra fine particles are generated by induction heating, archeating, resistance heating, or the like. The ultra fine particles madeof high melting point materials exemplified by zirconium (Zr) orvanadium (V) may be possibly used as non-evaporating getters due totheir specific surface size (see JP-A-2000-208033). For such a highmelting point metal, arc heating works effectively.

In a case of forming electrical wiring by gas deposition using silver(Ag) or aluminum (Al) which is not the high melting point material, archeating works also effectively in view of film deposition at high ratewith more evaporation.

For arc heating, usually, as shown in FIG. 5, the ultra-fine particlegeneration chamber includes an electrode arm, at the tip of which isattached with a tip-pointed rod electrode 101. Then, generally,discharge is caused between the tip of the rod electrode 101 and amaterial 8 to be evaporated (see JP-A-2000-17427 and Japanese Patent No.2596434).

Here, in FIG. 5, a reference numeral 13 denotes a carbon-made hearthliner (carbon-made container) having a concave part on which thematerial 8 is placed. A reference numeral 12 denotes a part where thematerial 8 is to be melted.

To maintain the stable evaporation of the material 8, the rod electrode101 is so angled as to form a few tens of degrees in the verticaldirection with respect to the material 8.

When the rod electrode 101 is put in an upright position, lengthwise,with respect to the surface of the material 8, the evaporated material 8tends to adhere to the rod electrode 101. This results in deformation ofthe tip of the rod electrode 101 which renders evaporation of thematerial 8 unstable.

Conversely, when the rod electrode 101 is put in a parallel position,lengthwise, with respect to the surface of the material 8, the generatedultra fine particles are blown off in the direction opposite to the rodelectrode 101. As a result, the particle smoke, i.e., the ultra-fineparticle flow, becomes difficult to be sucked up into the transfer tubelocated above the material 8.

FIG. 6 is a diagram for illustrating the state of the generatedultra-fine particle smoke, i.e., the ultra-fine particle flow, 14.

In FIG. 6, by putting the rod electrode 101 into a horizontal positionfrom the state shown in FIG. 6, i.e., by putting the rod electrode 101into a parallel position, lengthwise, with respect to the surface of thematerial 8, the generated ultra fine particles start being blown off inthe direction opposite to the electrode 101, i.e., the directionindicated by an arrow 15. This makes the ultra-fine particle smoke 14difficult to be sucked up into a transfer tube 3 located above thematerial 8.

This tendency becomes more noticeable with the higher arc voltage, andwith the larger angle of the rod electrode 101 with respect to thevertical direction, i.e., as the rod electrode 101 becomes moreparallel, lengthwise, with respect to the surface of the material 8.

Such a phenomenon may be caused by the collision of the flow of thethermoelectron emitted from the rod electrode 101 and the generatedultra-fine particle smoke 14. Such a collision may blow off the ultrafine particles in the direction opposite to the electrode 101.

Therefore, conventionally, to achieve the more efficient leading of theparticle smoke 14 to the suction part of the transfer tube, the rodelectrode 101 is angled about 30 to 45 degrees with respect to thevertical direction as shown in FIG. 6. In addition, applied is a methodfor adjusting the arc voltage and the arc current values.

SUMMARY OF THE INVENTION

The above conventional technology, however, carries the followingproblems.

In such a method as shown in FIG. 6, the arc electrode, i.e., rodelectrode, 101 is so located as to form an appropriate angle withrespect to the surface of the material 8, and arc discharge is causedbetween the material 8. Assuming that the arc current is constant, thehigher arc voltage, the larger the energy of the thermionic currentcoming from the rod electrode 101 becomes. If this is the case, theparticle smoke 14 is strongly bent in the direction further away fromthe rod electrode 101, i.e., in the direction of the arrow 15.Consequently, the particle smoke 14 becomes difficult to be sucked upinto the transfer tube 3.

Thus, to achieve the more efficient suction of the particle smoke 14into the transfer tube 3, the distance between the electrode and thematerial has to be adjusted to keep the arc voltage low. This adjustmenthas to be done while visually checking the particle smoke 14 to bealways within the range covered by the suction part of the transfer tube3. Consequently, the characteristics of arc heating method allowing filmdeposition at high rate cannot be fully taken advantage of.

Moreover, considered is a case of film deposition in line by ejectingthe ultra fine particles from the nozzle onto a moving substrate in thefilm deposition chamber. In this case, if the ultra-fine particle smoke14 is sucked up at the edge portion of the transfer tube 3, the crosssection of the resulting linear film may has a shape with a peak of filmthickness shifted to the edge portion thereof.

This shift of film thickness is depending on the part of the transfertube 3 where the particle smoke 14 is sucked up. As the suction part iscloser to the edge portion of the transfer tube, a peak of filmthickness tends to be further shifted to the edge portion in the crosssection of the resulting film.

Furthermore, this shift is sensitive to the voltage. Even a slightvoltage fluctuation will affect the direction the particle smoke 14goes. Thus, it has been difficult to obtain a film whose cross sectionis stable in shape.

The present invention is proposed to solve the above problems, and anobject thereof is to provide a film deposition apparatus and a filmdeposition method for forming particles by arc heating. With the filmdeposition apparatus and method, the resulting particles can beefficiently sucked up into a transfer tube regardless of an arc voltage,and the resulting film can be stable in shape.

One aspect of the present invention is a film deposition apparatus fordepositing a film by generating arc discharge by a potential differencebetween a first and second electrodes, evaporating a material by the arcdischarge, generating particles from the evaporated material andcolliding the particles against a substrate, the material beingelectrically connected to the second electrode, and the first electrodebeing provided with a plurality of sub-electrodes, wherein tips of theplurality of sub-electrodes are directed in directions different fromeach other with respect to the material.

It is preferable that the tips of plurality of sub-electrodes aredirected in directions different from each other with respect to avertical direction of a surface of the material.

It is preferable that the plurality of sub-electrodes are so provided asto heat substantially the same part of the material.

It is preferable that the plurality of sub-electrodes are providedapproximately radially to a specific part of the material.

It is preferable the plurality of sub-electrodes are rod electrodesarrange in different lengthwise directions.

It is preferable that the sub-electrodes each include any one materialW, Ta, Mo, or C.

It is preferable to further comprise: a first chamber in which the firstelectrode and the material are placed; a second chamber in which thesubstrate and a stage to which the substrate is fixed are placed; and atransfer tube for connecting the first chamber and the second chamber.

another aspect of the present invention is a film deposition method,comprising the steps of: (A) preparing a first electrode including aplurality of sub-electrodes, a second electrode, and a materialelectrically connected to the second electrode and evaporated by arcdischarge; (B) evaporating the material by causing the arc dischargesimultaneously among the material and the plurality of sub-electrodes;(c) generating particles from the evaporated material; and (D) collidingthe particles against a substrate, wherein each of the plurality ofsub-electrodes are faces the material in mutually different directions.

It is preferable that tips of the plurality of sub-electrodes aredirected in directions different from each other with respect to avertical direction of a surface of the material.

It is preferable that the plurality of sub-electrodes each heatsubstantially the same part of the material.

It is preferable that the plurality of sub-electrodes are providedapproximately radially to a specific part of the material.

It is preferable that the plurality of sub-electrodes are rod electrodesarranged in different lengthwise directions.

It is preferable that the sub-electrodes each include any one materialW, Ta, Mo, or C.

It is preferable to further comprise the steps of: preparing a firstchamber in which the first electrode and the material are placed;preparing a second chamber in which the substrate and a stage to whichthe substrate is fixed are placed; preparing a transfer tube forconnecting the first chamber and the second chamber; and setting apressure of the second chamber lower than a pressure of the firstchamber.

In the present invention, each sub electrodes are arranged at mutuallydifferent direction with respect to a material. In an exemplarystructure, the sub electrodes are arranged so that the material issurrounded, and a vector sum of thermionic current from the tips of thesub electrodes (discharge sections) is directed to any one specific partof the material (preferable if directed in the vertical direction of thematerial surface). With such a structure, no matter what arc voltage isto be applied, the ultra-fine particle smoke (particle flow) generatedby arc discharge is not blown off into a wrong direction but efficientlysucked up into a transfer tube with the carrier gas flow coming from thebottom part of the evaporation source. Further, the particle smokebecomes easier to be sucked up into the center of the suction part ofthe transfer tube. Accordingly, the resulting film can be stable inshape, and the cross section thereof is thicker in the center.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for illustrating the structure of a ultrafine particle film generation apparatus according to an embodiment ofthe present invention;

FIGS. 2A and 2B are both schematic diagrams showing an electrodeprovided with four discharge sections in Example 1;

FIGS. 3A and 3B are both schematic diagrams showing an electrodeprovided with eight discharge sections in Example 2;

FIGS. 4A to 4D are schematic diagrams showing an electrode provided withthree discharge sections in Example 3;

FIG. 5 is a schematic diagram showing an electrode whose tip is pointedaccording to the prior art; and

FIG. 6 is a schematic diagram showing the state of a ultra-fine particlesmoke generated from a material flowing into a direction opposite to anelectrode when arc power is increased.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the below, a preferred embodiment of the present invention isdescribed by way of example referring to the accompanying drawings.Herein, constituents are not restrictive in size, material, shape, andrelative layout to those described in the following embodiment, and itis understood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

FIG. 1 shows a schematic diagram showing the structure of a filmdeposition apparatus according to the embodiment of the presentinvention. The film deposition apparatus of the present embodiment ischaracterized in having gas deposition applied thereto.

In FIG. 1, a reference numeral 1 denotes a first chamber (sometimesreferred to as “particle generation chamber”), and a reference numeral 2denotes a second chamber (sometimes referred to as “particle filmdeposition chamber”). The reference numeral 3 denotes the transfer tube,and a reference numeral 4 denotes a nozzle attached to the tip of thetransfer tube 3 placed in the second chamber. Here, the nozzle 4 may bea member provided separately from the transfer tube, or the tip of thetransfer tube may be shaped nozzle as a substitute therefor. A referencenumeral 5 is a first electrode for arc discharge, and at the tipthereof, a plurality of rod-shaped sub electrodes are provided. Areference numeral 6 denotes first pressure control means for controllingthe pressure in the first chamber 1, and a reference numeral 7 denotes acarrier gas cylinder containing carrier gas exemplified by inert gas.The reference numeral 8 denotes the material to be evaporated by arcdischarge, and the material is sometimes referred to as “evaporationmaterial”. The material is electrically connected to a second electrode,which is not shown. A reference numeral 9 denotes a stage to which asubstrate 10 is fixed. A reference numeral 11 denotes second pressurecontrol means for controlling the pressure in the second chamber 2. Notehere that, the pressure inside of the first chamber 1 is maintained in astate higher than the pressure inside of the second chamber 2. Applyingany desired voltage between the first and second electrodes will causearc discharge between the tips of the sub electrodes and the evaporationmaterial 8, thereby causes an evaporation from a part of the material 8continuously. Then, collision between atoms as a result of evaporationof the material 8 and the carrier gas will generate the ultra fineparticles. The generated ultra fine particles are sucked up from the tipof the transfer tube utilizing the pressure difference between the firstand second chambers, and transferred into the second chamber. Then,through the nozzle at the tip of the transfer tube 3 located in thesecond chamber, the particles are ejected toward the substrate 10. Insuch a manner, a film is formed on the substrate 10.

FIG. 1 shows an example in which the particle generation chamber 1 inwhich the material (evaporation material) 8 is placed on a carbon-madehearth liner (carbon-made container) 13 connected to second electrode.

The material 8 in the particle generation chamber 1 is heated andevaporated by arc discharge caused by the voltage applied between thearc heating electrode (first electrode) 5 and the second electrodeconnected to the liner (container) on which the material 8 is placed.

Further, the particles thus generated in the particle generation chamber1 are led to the particle film deposition chamber 2 together with thecarrier gas via the transfer tube 3. Here, in the present invention,“fine particles” and “particles” are those, preferably, each ranging indiameter from a few nm to several μm. Then, in the particle filmdeposition chamber 2, the particles are ejected at high speed from thenozzle 4 attached to the tip of the transfer tube 3 together with thecarrier gas (helium gas 7). In this manner, a fine particle film isformed on the substrate 10 attached to the stage 9 for, film depositionthereon.

The stage 9 controllably moves toward the nozzle 4, and in the directionapproximately orthogonal to the nozzle 4.

At the time of film deposition, heating the substrate 10 is preferablebecause forming of a film on the substrate is improved. Similarly, filmheating and melting during or after film deposition is also preferablefor better film attachment.

The electrode 5, which is the structural characteristic of the presentembodiment, is provided with a plurality of rods (sub-electrodes) at thetip thereof to be used as a plurality of electrodes each including adischarge section. Here, it is preferable if each of the rod tips facesthe material 8 in mutually different directions. In the presentinvention, the rods are preferably directed, lengthwise, to directionsdifferent from each other with respect to the material 8.

Similarly, it is preferable if each discharge section is arranged insuch a direction as to heat substantially the same part of the material8. In other words, the rods are each directed, lengthwise, toward thesame part of the material 8, that is, the melting part 12.

It is also preferable if the discharge sections are providedapproximately radially to any one specific part of the material 8. Inother words, it is preferable if the rods are directed, lengthwise, toany one specific part of the material 8, i.e., the melting part 12, andare provided approximately radially around the part.

In the following examples, the arc heating electrode 5, which is thestructural characteristic of the present embodiment, is described inmore detail. Note here that, any constituent already described in theRelated Art section and Preferred Embodiment is provided with the samereference numeral, and not described again.

EXAMPLE 1

FIGS. 2A and 2B are both schematic diagrams showing the arc heatingelectrode 5 of the Example 1. The arc heating electrode 5 of Example 1is configured by four sub electrodes (rod electrodes) 17. FIG. 2A is aperspective view, and FIG. 2B is a plan view. The general constructionof the film deposition apparatus is equivalent to that schematicallyshown in FIG. 1.

As shown in FIGS. 2A and 2B, in this example, to use as the arc heatingelectrode (first electrode) 5 has a circular tungsten-made ring 16 withfour 1 mm-diameter tungsten-made rods (sub electrodes) 17 fixed thereon.The tungsten-made rods 17 are so arranged that the tips thereof eachform, lengthwise, an angle of approximately 45 degrees with respect tothe vertical direction of the surface of the material 8. Further, therods 17 are fixed on the circular tungsten-made ring 16 using screws sothat the rod tips direct to the melting part 12 of the material 8. Inthis example, with such an arc heating electrode 5 an electrical wiringis formed by deposition of ultra fine Ag particles. For comparison,another electrical wiring is formed with the tip-pointed rod electrode101 of the conventional type as shown in FIG. 5.

At the time of film deposition, the current value is kept constant, andthe voltage is the parameter, changing the distance between the materialand the tip of the electrode 5, i.e., tips of the rod electrodes.

To see whether the generated ultra fine particles are discharged fromthe nozzle 4 via the transfer tube 3, film is deposited in line throughthe constant movement of the substrate 10. Then, a sensing-pin type filmthickness measurement device is used to measure the film thickness andthe cross sectional shape of the deposited film.

Conditions of the film deposition are as follows:

Nozzle Size: circular aperture of 1 mm in diameter

Pressure in Ultra-Fine Particle Generation Chamber: 530 Torr (70490 Pa)

Pressure in Film Deposition Chamber: 1.2 Torr (159.6 Pa)

Arc Current: 50 A

Substrate Movement Speed: 0.1 mm/sec

Table 1 shows the voltage dependency result of the film thickness of thelinear electrode deposited with the electrode including four rods. TABLE1 Voltage(V) 20 24 28 32 34 Film Thickness (μm) 20 22 25 31 38 withElectrode of Example 1 Film Thickness (μm) 11 12 0 0 0 with ConventionalElectrode

Table 1 shows that no film is deposited under the voltage 28V or higherwith the conventional type electrode used to generating the ultra fineparticles.

This is because the ultra-fine particle smoke (particle flow) formed byevaporation of the material 8 is blown off in the direction opposite tothe first electrode 101, and thus is not sucked up into the transfertube 3. This phenomenon is visually observed as well.

On the other hand, in the case of generating the ultra fine particleswith the first electrode 5 of this example, most of the ultra-fineparticle smoke (particle flow) goes up directly above the material 8,and sucked up into the transfer tube 3. This is visually observed.

Such results tell that the electrode 5 of this example can efficientlyallow the generated ultra fine particles to be sucked up into thetransfer tube 3.

The results also tell that, the higher the voltage, the thicker theresulting wiring filmed using the electrode of this example becomes.Also, as the arc voltage at the time of film deposition is increased,wiring film deposition can be achieved at higher rate.

Further, the resulting wiring deposited with the conventional electrodeunder 20V or 24V has a cross section of a shape with a peak of thicknessshifted from the center to the edge, and the edge part is thicker thanthe center part. The cross section of a line deposited under 24V has ashape with a peak of thickness further shifted to the edge compared withthat deposited under 20V.

On the other hand, the resulting wiring filmed using the electrode ofthis example stably has a cross section which has a peak of thickness inthe central part regardless of the voltage.

EXAMPLE 2

FIGS. 3A and 3B are both schematic diagrams showing the first electrode(arc discharge electrode) 5 of this example, more specifically, showingthe first electrode 5 configured by eight sub electrodes 19. FIG. 3A isa perspective view, and FIG. 3B is a plan view. The general constructionof the film deposition apparatus in its entirety is equivalent to theone schematically shown in FIG. 1.

As shown in FIGS. 3A and 3B, in this example, an octanglemolybdenum-made jig 18 is provided with eight holes, at equal intervals,to allow 1 mm-diameter rod electrodes (sub electrodes) 19 to passtherethrough. As the rod electrodes 19, used are 1 mm-diameter eighttungsten-made rods 19 to which yttrium oxide (Y₂O₃) is doped. Here, therod electrodes 19 are so arranged that the tips thereof each form,lengthwise, an angle of approximately 45 degrees with respect to thevertical direction of the surface of the material 8. Further, to havethe rod tips direct to the melting part 12 of the material 8 so that therod electrodes 19 are fixed to the octangle molybdenum-made jig 18 withscrews. Using such an arc discharge electrode 15 and the material 8mainly made of Ag, a mirror is produce out of ultra fine Ag particles.

Used as the substrate 10 is a BK7 substrate, and the back of a glasssubstrate is utilized for the mirror.

As the nozzle 4, used is a nozzle having as lit-shaped aperture, and thesubstrate is moved in a direction perpendicular to the longer side ofthe aperture.

For comparison, a film is deposited with such a tip-pointed arcdischarge electrode 101 of the conventional type as shown in FIG. 5,made of tungsten to which yttrium oxide (Y₂O₃) is doped.

Conditions of the film deposition are as follows:

Nozzle Size: aperture 300 μm×5 mm slit type

Pressure in Ultra-Fine Particle Generation Chamber: 530 Torr (70490 Pa)

Pressure in Film Deposition Chamber: 1.0 Torr (133 Pa)

Arc Current: 25 A

Substrate Movement Speed: 1.25 mm/sec

Substrate Temperature: 300 degrees

After film formation, the resulting linear film having a width of 5 mmis evaluated by average thickness, reflectance in visible regions, andvisual inspection of the back surface. TABLE 2 Voltage(V) 22 24 26 28 30Average Film Thickness 0.72 0.76 0.82 0.90 0.94 (μm) with Electrode ofExample 2 Reflectance (%) 95.3 95.3 95.6 95.6 95.7 Visual InspectionNothing Nothing Nothing Nothing Nothing Wrong Wrong Wrong Wrong Wrong

TABLE 3 Voltage(V) 22 24 26 28 30 Average Film Thickness 0.15 0.14 0 0 0(μm) with Conventional Electrode Reflectance (%) 94.8 94.8 8.2 8.2 8.2Visual Inspection Uneven- Uneven- No No No ness ness Film Film FilmObserved Observed

Table 2 shows the film thickness, reflectance with 500 nm wavelength,and visual inspection of the mirror produced with the arc dischargeelectrode 5 (see FIGS. 3A and 3B) of this example, and Table 3 showsthose of the mirror produced with the arc discharge electrode 101 (seeFIG. 5) for comparison.

The reflectance in Table 2 tells that the film deposited with theelectrode of this example has a mirror plane regardless of the voltage.Moreover, visual with result tells that the mirror plane is evenlyreflective in the visual regions regardless of the voltage. In thetable, the average film thickness is increased as the voltage getshigher. This is because the evaporation is increased due to the higherarc power. Further, we visually observed that the ultra-fine particlesmoke formed as a result of evaporation of the material is sucked upinto the center part of the transfer tube 3 no matter what voltage isapplied.

On the other hand, with the film deposited with the conventionalelectrode shown in Table 3, we visually observed that the ultra-fineparticle smoke generated under the voltage of 26V is blown off in thedirection opposite to the electrode and is not sucked up into thetransfer tube. The film thickness and reflectance evaluations show that,with the voltage of 26V or higher, no complete film is deposited on thesubstrate. In the table, the reflectance is 8.2% under the voltage of26V or higher. This is because reflections occur to the front and backsurface of the substrate itself.

As is known from the above, discharge caused by the electrode of thisexample allows particle films to be deposited in a stable mannerregardless of the voltage.

EXAMPLE 3

FIGS. 4A to 4D are all schematic diagrams showing the arc heatingelectrode (first electrode) 5 of this example. In this example, threerod electrodes 21 are used as the sub-electrodes. FIG. 4A is aperspective view, FIG. 4B is a plan view, FIG. 4C is a perspective viewof a rod electrode 21, and FIG. 4D is a plan view of the rod electrode21. The general construction of the film deposition apparatus isequivalent to the one schematically shown in FIG. 1.

In this example, the sub-electrode configured by three carbon rods 21 isused to produce a mirror out of ultra fine Al particles.

The carbon rod 21 is 1 mm in diameter. As shown in FIG. 4C, two of thethree rod electrodes 21 are so fixed as to form an angle of 30 degreeswith respect to the vertical direction of the surface of the material 8.The remaining one electrode is so fixed as to form an angle of 45degrees with respect to the vertical direction of the surface of thematerial 8. The angles between the rods are not the same, and as shownin FIGS. 4B and 4D, the angles viewed from the above are 90°, 135°, and135°.

Similarly to Example 2, the nozzle 4 having a slit-shaped aperture andthe BK7 substrate are used. The substrate is moved in a directionperpendicular to the longer side of the aperture. The back surface ofthe film plane is evaluated as a mirror in the visual regions.

For comparison, another mirror is produced with such an arc dischargeelectrode as shown in FIG. 5, which is carbon-made conventionaltip-pointed rod electrode 101 of 5 mm in diameter.

Condition of the film deposition is as follows:

Nozzle Size: aperture 300 μm×5 mm slit type

Pressure in Ultra-Fine Particle Generation Chamber: 800 Torr (106400 Pa)

Pressure in Film Deposition Chamber: 2.2 Torr (292.6 Pa)

Arc Current: 20 A

Substrate Movement Speed: 1.25 mm/sec

Substrate Temperature: 300° C.

Under such conditions, the linear thin film is deposed out of the ultrafine particles ejected from the nozzle 4 while moving the substrate 10.Similarly to Example 2, the resulting film is subjected to filmthickness check, reflectance check in the visible regions, and visualinspection.

Table 4 shows the results derived from the electrode of this exampleshown in FIGS. 4A to 4D, and Table 5 shows the results derived from theelectrode used for comparison.

Note here that, the reflectance shown in Tables 4 and 5 are values withthe wavelength of 500 nm. TABLE 4 Voltage(V) 22 24 26 28 30 Average FilmThickness 0.32 0.30 0.33 0.46 0.55 (μm) with Electrode of Example 3Reflectance (%) 90.1 90.5 90.2 90.3 90.6 Visual Inspection NothingNothing Nothing Nothing Nothing Wrong Wrong Wrong Wrong Wrong

TABLE 5 Voltage(V) 22 24 26 28 30 Average Film Thickness 0.36 0.41 0 0 0(μm) with Conventional Electrode Reflectance (%) 90.6 90.3 8.2 8.2 8.2Visual Inspection Uneven- Uneven- No No No ness ness Film Film FilmObserved Observed

Table 4 tells that the film deposited with the electrode 5 of thisexample has a mirror surface regardless of the voltage. Moreover, weobserved that the generated particle smoke (particle flow) is sucked upinto the center part of the transfer tube 3 regardless of the voltage.In addition, visual inspection result of the back surface tells that themirror plane is evenly reflective in the visual regions.

On the other hand, with respect to the film deposited for comparisonwith the conventional electrode shown in Table 5, we observed similarlyto Example 2 that the particle smoke generated under the voltage of 26Vor higher is blown off in the direction opposite to the electrode 101and is not sucked up into the transfer tube.

The film thickness and reflectance evaluations show that, with thevoltage of 26V or higher, no complete film is deposited on thesubstrate. In the table, the reflectance is 8.2% under the voltage of26V or higher. This is because reflections occur to the front and backsurface of the substrate itself.

As is known from the above, discharge caused by the electrode of thisexample allows particle films to be deposited in a stable mannerregardless of the voltage.

As described above, the present embodiment employs a gas depositionmethod in which a metal material is evaporated by arc heating, particles(ultra fine particles) are generated out of the evaporated material, anda film is deposited with the generated particles (ultra fine particles)to form wirings, electrodes, and optical films. Then, under such a gasdeposition method of this embodiment enables the resulting particles(ultra fine particle) to be efficiently sucked up into a transfer tuberegardless of an arc voltage at the time of particle generation.

Further, even a slight voltage fluctuation occurs, suction into thecenter part of the transfer tube can be stably achieved. Therefore, atthe time of linear film deposition through movement of the substrate,the cross section of the film can be stable in shape.

As described in the above, according to the present invention,regardless of the arc voltage at the time of particle generation, theresulting particles can be efficiently sucked up into the transfer tube.

Further, at the time of linear film deposition through movement of thesubstrate, the cross section of the film can be stable in shape.

1-14. (canceled)
 15. A method of forming a film comprising the steps of:(a) preparing a first electrode having at least two sub-electrodes, asecond electrode, and a material electrically connected to the secondelectrode. (b) evaporating the material by causing the arc dischargebetween the material and the first electrode; (c) generating particlesfrom the evaporated material; and (d) colliding the particles against asubstrate, wherein each of the sub-electrodes is a aligned towardsubstantially the same portion of the material.
 16. The method accordingto claim 15, wherein the sub-electrodes each heat substantially the sameportion of the material.
 17. The method according to claim 15, whereinthe plurality of sub-electrodes are in substantially radial alignment tothe substantially same portion of the material.
 18. The method accordingto claim 15, wherein the sub-electrodes are rod-like electrodes.
 19. Themethod according to claim 15, wherein the sub-electrodes each includeany one material W, Ta, Mo, or C.
 20. The method according to claim 15,further comprising the steps of: preparing a first chamber in which thefirst and the second electrodes and the material are placed; preparing asecond chamber in which the substrate and a stage to which the substrateis fixed are placed; preparing a tube for connecting the first chamberand the second chamber with a tube; and setting a pressure of the secondchamber lower than a pressure of the first chamber.